According to Bleeding Green Nation, the Eagles made the move primarily because of the injury sustained in the season opener by Jeremy Maclin. While Maclin might be ready for Week 2 against the Baltimore Ravens, it's not a chance the team can take.
Unfortunately for Jarrett, his time has run out with Philadelphia. The once promising prospect never really panned out and was only active for 12 games to this point in his brief career. In that time, Jarrett amassed only 22 tackles.
The Eagles are alright in regards to depth at safety with four still on the roster. Kurt Coleman and Nate Allen are obviously the starters, with the newly-signed David Sims as the primary backup should either of them go down. S Colt Anderson is on the 53 man roster but has been rehabbing a knee injury, although he is primarily a special teamer.